It is well known to the prior art to provide furnace heat exchange systems in which the products of combustion (exhaust) are passed through the furnace in a zig-zag fasion. This is shown in the following patents.
(1) Bartlett U.S. Pat. No. 101,082 "Hot Air Furnace," Issued Mar. 22, 1870;
(2) Twitchell et al U.S. Pat. No. 559,918, Issued May 12, 1896 for "Heating and Ventilating Furnace";
(3) Kuhner U.S. Pat. No. 2,479,940 "Multiple Tube Air Heating Furnace" Issued Aug. 23, 1949;
(4) Feuerfile U.S. Pat. No. 2,504,315 "Fluid Heater and Thermostatic Control Means Therefor," Issued Apr. 18, 1950; and
(5) Eichhorn U.S. Pat. No. 2,685,875 Issued Aug. 10, 1954 for "Warm Air Heating Furnace."
Further, it is known to provide furnaces or systems in which the air to be heated is passed through the furnace in a zig-zag manner. This is seen in the following patent:
(1) Bartlett U.S. Pat. No. 12,305 "Hot Air Furnace," Issued Jan. 30, 1855;
(2) Wallace U.S. Pat. No. 54,795 "Hot Air Furnace," Issued May 15, 1866;
(3) Engels et al U.S. Pat. No. 63,490 Issued Apr. 2, 1867 for "Hot Air Furnace."
Yet further, furnace systems are well known in which both the air to be heated and the products of combustion zig-zag through the furnace construction. Such are seen in the following patents:
(1) Pessenger U.S. Pat. No. 346,770 Issued Aug. 3, 1886 for "Heating Furnace";
(2) Smith U.S. Pat. No. 2,290,255 Issued July 21, 1942 for "Furnace";
(3) Norton U.S. Pat. No. 2,363,742, Issued Nov. 28, 1944 for "Furnace"; and
(4) Powers U.S. Pat. No. 2,225,181, Issued Dec. 17, 1940 for "Heating and Air Conditioning Unit."
The subject systems and apparatus are designed to provide improvements in the extraction of heat which are not known to the prior art and which will provide and achieve energy conservation effects of significant magnitude in the most simple and conventional present day systems which are not capable of functioning with the efficiency which the future will require.